Material for use in oil refining and method of making it



Patented Aug. 25, 1936 MATERIAL FOR USE IN OIL DEFINING AND METHOD OF MAKING IT Ralph W. Miller, Barherton, Ohio, assignor to Pittsburgh Plate Glass Company, a corporation of Pennsylvania No Drawing. Application April 29, 1933.

Serial No. 668,633

1 Claim. (Cl. 252-1) This invention relates to the production of cooledto'l0 F. A 15.5% pure causticsodasolusodium plumbite or doctor solution possessing novel properties from waste caustic alkali liquors.

tion treated in a similar manner contained only 4.0% PhD at 200 F. and.2.-6% PbO at 70 F. After standing for thirty (30) days, the doctor" Doctor solution is used by the petroleum insolution prepared from rayon waste caustic liqdustry for treating their products in a step uor contained 4.2% PbO. This decrease was due called the sweetening process. At present to a slow crystallization of PhD which took place. doctor solution is made by agitating an 941- Example B.One thousand parts by weight of proximately twenty-five (25%) per cent hot rayon waste caustic liquor containing 15.5%

10 caustic soda solution with litharge which results NaOH and the usual amount of impurities were in an alkaline solution of sodium plumbite. In concentrated by adding 127 parts by weight of preparing such solutions it is desired to dissolve solid caustic soda so that the concentration of as much litharge as possible; however, the max- 139,011 was increased to 25%. This liquor was imum solubility is about flve (5%) per cent. then heated to near its boiling point and 200 In the manufacture of rayon by the viscose parts by weight of litharge were added. After 15 process, raw cellulose is first steeped in an apagitating a few minutes, the precipitate which proximately eighteen (18%) per cent caustic formed and the excess litharge were removed soda solution. The excess alkali is removed by centrifuging and decanting off the clear sotherefroin and constitutes the rayon waste dium plumbite solution. Analysis showed this 20 caustic liquor. This liquor contains in addiclear solution to contain about 11.7% PbO even 20 tion to the caustic soda several per cent of imwhen cooled to 70 F. A pure caustic soda purities which are mostly organic and probably solution treated in a similar manner contained consist of cellulosic materials, resins and the 5% PhD at 200 F. and 2.3% PbO at 70 F like. Thus far these impurities have been very After standing for thirty days at 70 F. this 25 diilicult to remove from the caustic at a cost low doctor solution contained 8.6% PhD. The high 25 enough to be commercially feasible. content of PhD resulting from the process is be- I have found that a "doctor" solution possesslieved to be due to a certain amount of organic ing novel properties can be prepared from this material which remains in the caustic soda solurayon waste liquor. The procedure is similar tion and which tends to increase the amount of 30 .to that of regular practice except that a precipitate containing organic matter and lead forms and may be removed by filtration or otherwise. By burning this precipitate, either metallic lead or litharge results depending on the amount of air accessible. The litharge used in forming this precipitate is not lost but may be recovered by this method and used for the treating of a further portion of waste caustic liquor. The filtrate, which constitutes my "doctor solution, will contain considerably more lead than that prepared from a pure caustic soda solution of the same concentration of NaOH as evidenced by the examples A and B set forth below.

The following examples illustrate the use of rayon waste caustic liquor in the production of my doctor" solution:

Example A.-One thousand parts by weight of rayon waste caustic liquor containing 15.5% NaOH and the usual amount of impurities were heated to near its boiling point, after which 150 parts by weight of litharge were added. After agitating for a few minutes, the precipitate which formed and the excess litharge were removed by centrifuging and decanting oi! the clear sodium plumbite solution. Analysis showed this solution to contain about 9% PhD evem when litharge held in colloidal sispension.

This invention is useful because "doctor" solutions containing several-fold more PbO than usual may be economically prepared from a cheap source of waste alkali. This also aflords an opportunity for the disposal of such waste caustic liquors.

Although this invention is described in conjunction with the preparation of "doctor" solution from rayon waste caustic liquor, it is not limited thereto but also includes the use of waste caustic liquors from other steeping processes as well as the use of pure caustic soda solutions treated to give properties such as those of rayon waste caustic liquor. The term doctor" solution is intended to include solutions resulting from the treatment of caustic soda solutions with litharge. By rayon waste caustic liquor I mean the product derived from the steeping operation in the viscose process for making rayon.

What I claim is:

A doctor solution comprising PhD and impure rayon waste as it comes directly from the viscose process containing in part substantially 15.5% caustic soda. said doctor solution containing from about 4.24% of PhD at '10 degrees F.

RALPH W. MILLER. 

